#include"my_stdio.h"
#include<string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

//初始化
static MyFile* BuyFile(int fd, int flag)
{
    MyFile* f = (MyFile*)malloc(sizeof(MyFile));
    if(f == NULL)   return NULL;
    f->bufferlen = 0;
    f->fileno = fd;
    f->flag = flag;
    f->flush_method = LINE_FLUSH;
    memset(f->outbuffer, 0, sizeof(f->outbuffer));
    return f;
}
MyFile* MyFopen(const char* path, const char* mode)
{
    int fd = -1;
    int flag = 0;
    if(strcmp(mode, "w") == 0)
    {
        flag = O_CREAT | O_WRONLY | O_TRUNC;
        fd = open(path, flag, 0666);
    }
    else if(strcmp(mode, "a") == 0)
    {
        flag = O_CREAT | O_WRONLY | O_APPEND;
        fd = open(path, flag, 0666);
    }
    else if(strcmp(mode, "r") == 0)
    {
        flag = O_RDWR;
        fd = open(path, flag);
    }
    else
    {
        //todo
    }
    if(fd < 0)  return NULL;
    return BuyFile(fd, flag);
}
void MyFclose(MyFile* file)
{
    if(file->fileno < 0) return;
    MyFflush(file);
    close(file->fileno);
    free(file);
}
int MyFwrite(MyFile* file,void* str, int len)
{
    //1.拷贝
    memcpy(file->outbuffer+file->bufferlen, str, len);
    file->bufferlen += len;
    //2.刷新
    if((file->flush_method&LINE_FLUSH) && (file->outbuffer[file->bufferlen-1] == '\n'))
    {
        MyFflush(file);
    }
    return 0;
}
void MyFflush(MyFile* file)
{
    if(file->bufferlen <= 0)    return;
    //把用户的数据拷贝到内核文件缓冲区
    int n = write(file->fileno, file->outbuffer, file->bufferlen);
    (void)n;
    fsync(file->fileno);
    file->bufferlen = 0;
}